Method for producing evacuated glass microspheres
Abstract
Abstract A method is provided for the production of low density, internally coated, evacuated microspheres wherein the sphere density is uniform and the sphere diameter and wall thickness can be controlled accurately. In a preferred embodiment of the instant method, molten glass (or other suitable nonmetallic material) is used to encapsulate zinc or another suitable metal in either the solid or liquid state. After the metal has been encapsulated the temperature of the particle is increased until the encapsulated metal vaporizes and blows the particles into thin-walled, hollow spheres which are then quenched so that the encapsulating walls become rigid before the condensing metal vapor on the inside of the walls causes the spheres to collapse.
Inventors
- 👤 Edwin F Coxe
Bibliographic Details
Claims Analysis
Total Claims: 2References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |